complementary function to unapply()

[Han]

(03-31-2015 06:33 PM)parisse Wrote:  leprechaun, if say f(x):=sin(x^2), in Xcas you can access to the expression with f[3] (for any symbolic f, f[0] returns the top-level operator/command, f[1], f[2], etc. the arguments, a function is a symbolic with top-level command 'program'). I did not check on the Prime, it might work as well but probably with an index shift, i.e. with f[4].

Just verified that it is indeed "shifted by 1". Very cool to have such a simple way of accessing parts of a function!